docs: def get_package_dir(self, package):
          """Returns the directory, relative to the top of the source
          distribution, where package ``package`` should be found
          (at least according to the :attr:`package_dir` option, if any).
  
          Copied from :meth:`distutils.command.build_py.get_package_dir()`
          method.
  
          """
          path = package.split('.')
          if not self.package_dir:
              if path:
                  return os.path.join(*path)
              return ''
          tail = []
          while path:
              try:
                  pdir = self.package_dir['.'.join(path)]
              except KeyError:
                  tail.insert(0, path[-1])
                  del path[-1]
              else:
                  tail.insert(0, pdir)
                  return os.path.join(*tail)
          else:
              pdir = self.package_dir.get('')
              if pdir is not None:
                  tail.insert(0, pdir)
              if tail:
                  return os.path.join(*tail)
              return ''